Sains Malaysiana 30: 119-133 (2001)                                                                           Sains Hayat/

        Life Sciences

Pembentukan Sebatian Pirazina melalui Tindak Balas Maillard

Antara Likur Koko dengan Glukosa dan Asid Amino

(Formation of Pyrazine Compounds Through Maillard Reaction Between Cocoa

 Liquor With Glucose and Amino Acids)

Nazaruddin Ramli Osman Hassan & Nor Azlina Abd Mutalib

Program Sains Makanan

Pusat Pengajian Sains Kimia & Teknologi Makanan

Fakulti Sains & Teknologi, Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor D.E., Malaysia

ABSTRACT

Empat model tindak balas telah dikaji dengan menggunakan empat jenis asid amino yang berlainan iaitu asid amino leusina, alanina, valina dan fenilalanina bagi melihat corak penghasilan sebatian meruap daripada kumpulan pirazina secara kualititatif dan kuantitatif yang bertindak balas dengan glukosa di dalam likur koko. Satu model kawalan telah dibentuk tanpa tambahan asid amino dan glukosa. Setiap model menerima 12 perlakuan dengan suhu dan masa yang berlainan dan sebatian meruap diekstrak menggunakan modifikasi kaedah pengekstraksian pelarut radas Likens dan Nickerson yang terubahsuai. Pengecaman sebatian meruap dilakukan menerusi analisis Kromatografi Gas untuk Lapan jenis komponen pirazina iaitu pirazina, 2-metilpirazina, 2,5­dimetilpirazina, etilpirazina, 2,3-demetilpirazina, 2,3,5-trimetilpirazina, 2­asetilpirazina dan 2,3,5,6-tetrametilpirazina. Analisis kuantitatif menunjukkan penggunaan asid amino leusina adalah paling baik untuk penghasilan maksimum sebatian meruap diikuti asid amino valina, fenilalanina dan alanina. Secara kualititatif, semua sebatian yang dikenalpasti hadir di dalam setiap model tindak balas yang dibentuk dan jumlah penghasilan sebatian meruap didapati berkait secara relatif dengan faktor suhu, masa dan jenis asid amino yang digunakan. Suhu 140^oC selama 30 min adalah perlakuan maksima untuk penghasilan jumlah sebatian meruap manakala suhu 130°C dalam tempoh 60 dan 90 min adalah perlakuan maksima untuk semua model tindak balas.

ABSTRAK

Four models of reaction were tested to investigate qualititatively and quantitatively the formation of pyrazine compounds. The investigation based on the reactions of flavour precursors and cocoa liquor during roasting. Four types of amino acids i.e leucine, alanine, valine and phenylalanine were reacted to the glucose in model system cocoa liquor-propylene glycol as flavour precursir components. Each model was given twelve treatments under various temperatures and reactions times. The volatiles were extracted using the modified of Likens and Nickerson solvent extractions methods. The gas chromatography analysis were used to identify the volatile compounds which were pyrazine, 2-methylpyrazine, 2,5-dimetyhlpirazine, ethylpirazine. 2,3-dimetylpirazine, 2,3,5-trimethylpyrazine, 2-acethy/pirazine and 2.3.5.6­ tetramethylpyrazine. Quantitative analysis showed that leucine produced the highest levels of volatile compounds followed by valine, phenylalanine and alanine. Quantitative analysis showed that all pyrazine compounds investigated were found in each reaction model. Temperatures, reaction time and also types of amino acids that were used relatively affected the production of volatile compounds. The optimum temperatures of volatile compounds production for 30 minutes reaction time was 140^oC while formation of volatile compounds for 60 minutes and 90 minutes reaction times were optimal at 130^oC in each model with the highest score showed by leucine.

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